64 CRETACEOUS GROUP 
PECTUNCULUS. 
1. P. hamula, (S.G.M.) PI. xv, fig. 7. 
Specific character. Subglobose, smooth and ponderous; 
posterior extremity angulated. 
Diameter, from three-fourths of an inch to an inch. 
Found by Mr. Conrad in the older cretaceous strata at 
Prairie Bluff, Alabama. 
2. P. australis, (S. G. M.) 
Specific character. Suborbicular, nearly equilateral, convex ; 
beaks small, pointed, slightly prominent, central; inner mar- 
gin crenulated. 
Found with the preceding, from which it differs in be- 
ing somewhat of a lenticular form; it is about the same 
size. It came too late to be figured. 
3. I possess casts of another species from the mart of 
New Jersey. 
ARCA. 
A. rostellata, (S.G. M.) Pl. ii, fig: 11. 
Specific character. Elongated, narrow, ventricose ; with nu- 
merous delicate coste radiating from the beaks to the margin; 
the latter having a subcentral, gaping constriction. 
Length, an inch and a quarter; breadth, five-eighths of an 
inch. 
From Alabama. 
CUCULLEA. 
1. C. vulgaris, (S.G. M.) Pl. iu, fig. 8: and a cast, 
pl. xiii, fig. 5. 
Specific character. Ventricose, ovato-triangular, flattened 
